Horizontal well production method with uniform flow

ABSTRACT

The invention addresses to a flow uniformization process for the entire useful life of a horizontal well, which associates the use of divergent sand containment screens or divergent liner. For the manufacture of divergent liners, flow simulations are carried out via computational fluid dynamics as a function of the dimensions of the horizontal well, outer diameter and length of the liner, static pressure, expected flow pressure, expected oil flow rate, oil viscosity, API degree, planned length for the horizontal well. These simulations simulate the area open to flow along the horizontal section. Additionally, well stimulation methods, scale removers and, optionally, sand containment are used.

FIELD OF THE INVENTION

The present invention is related to the field of production development in the management of reservoirs, associated with the control of production losses through production management, in the guarantee of production flow.

DESCRIPTION OF THE STATE OF THE ART

The technical problem that motivated the invention was the need of reducing the gas-oil ratio (GOR) of wells completed in oil reservoirs with large horizontal extensions.

In the case of horizontal producing and injection wells, these normally produce or inject with greater flow rate in the section closest to the beginning of the horizontal extension of the well, usually the shoe of the last casing. Given that this flow distribution is not homogeneous along the length of the horizontal well, the formation of gas cones may occur near the shoe of the last casing and thus increase the GOR of the wells early due to the influx of gas.

Depending on the type of reservoir, the wells will be completed with specific equipment to meet the well completion design. When wells are drilled in formations that produce sand, they require the installation of a mechanical sand containment system. Until now, the set of mechanical sand containment screens installed in the horizontal wells of PETROBRAS still do not have an adequate production uniformization system that provides a homogeneous distribution of the production and/or injection along the set of screens positioned within the well horizontal extension.

Prior to the invention, the wells were completed with equipment that did not have a flow uniformization design in the production string along the horizontal extension of the wells, as risks associated with the occurrence of the formation of gas cones and with this the very high production of GOR, in which the GOR increased inversely with the reduction in oil production in the wells where this phenomenon occurred. As the BSW (Basic Sediment and Water) from the wells appeared in the production of the wells, there was also a rapid growth due to the water cone.

The horizontal producing and injection wells produce or inject with greater flow rate in the section closest to the beginning of the horizontal extension of the well (shoe of the last casing). When these wells are drilled in formations that produce sand, they require the installation of a mechanical sand containment system. So far, the set of mechanical sand containment screens, installed in the horizontal wells (FIG. 1 ), still do not have an adequate production compensation system that provides homogeneous production and/or injection distribution along the set of screens, positioned within the horizontal extension of the well. FIG. 1 shows the shroud (protective layer of the sand filter) (1), which is the outer layer of protection for the filtration layer; filter layer (2); inner protective layer (3) for the filtration layer; screen perforated base tube (4).

The conventional screens currently used in horizontal producing and injecting wells are not manufactured taking into account the need of equalizing the flow along the horizontal extension of the well, as shown in the flow diagram in FIG. 2 , where the dashed arrow indicates the bottomhole pressure and the solid arrows indicate the reservoir pressure.

In the solutions known to date, screens with a base tube without holes (blind tubes) are used; so, in the case of the horizontal producing well, the oil flow leaves the producing formation, crosses the filtration layer of the screen and travels the annular space between the filtration layer and the outside of the base tube. In these two systems, flow controllers (choke) are used, which are designed to provide a pressure drop. This pressure drop is positioned in a decreasing way along the length of the well, that is, from the beginning of the well to the bottom, with the purpose of compensating the production to the equalization of the flow and/or the injection.

The disadvantages of the solutions presented in the state of the art are in relation to the need of future treatments, which will have to be done in the well, such as acidification treatments, to recover the production index or the injectivity index, and removal of scale deposition; in this case, we would not be able to guarantee the divergence that is necessary for an efficient result. Another point would be in the occurrences of scale depositions, which prefer to form at pressure drop points.

“DE SOUZA RIBEIRO, Heitor Lopes; ROMERO, Oldrich Joel. Estudo da furação diversiva em poços horizontais produtores de petróleo. Research, Society and Development, v. 8, no. 10, p. e248101362-e248101362, 2019” discloses a simulation performed using commercial software of computational fluid dynamics, with the objective of analyzing the pressure drop in the flow of a horizontal pipeline, arising from the interference of a radial inflow from the holes in the pipeline.

The document “MANTEGAZINI, Isabela Silva; ROMERO, Oldrich Joel. Analise do escoamento em poços horizontais injetores completados com a tecnica de furação diversiva. Research, Society and Development, v. 8, no. 9, p. e50891327-e50891327, 2019” discloses a computational fluid dynamics simulation using a horizontal pipeline with differentiated perforation to analyze the flow in horizontal injection wells completed with the divergent perforation technique, highlighting the effects of inertial and viscous forces on the pressure drop profile and, consequently, on the flow profile.

Document WO2017053335A1 discloses a technique that facilitates the control of fluid flow in relation to a sand screen assembly. The screen assembly may comprise a base tube, a sand screen disposed over the base tube and an inflow control device assembly. The inflow control device assembly comprises an inflow control device combined with a check valve in fluid communication with the inflow control device. The check valve is oriented to block the flow of fluid through the inflow control device in a given direction. Additionally, the inlet control device may be in the form of an autonomous inlet control device to provide different levels of flow control depending on the properties of the fluid.

Document BR 10 2021 022762-1 teaches a method of stimulating the reservoir with a wash tube tool with divergent perforation during the well completion step. This tool, however, is used for injecting chemicals into the reservoir to remove damage and scale, and then withdrawn after finishing of the completion of the oil well.

The prior art presented only addresses to unproven simulations or does not present production strings with screens with divergent perforation to uniformize the flow of a fluid and stimulate the production of the oil well permanently and throughout the life of the well.

In view of the difficulties present in the above-mentioned state of the art, and in order to seek solutions to permanently uniformize the flow in the production of the oil well during its useful life, there is a need of developing a technology capable of performing effectively and that complies with environmental and safety guidelines. The above-mentioned state of the art does not have the unique features that will be presented in detail below.

OBJECTIVE OF THE INVENTION

It is an objective to promote the production of a horizontal well so that the production flow is uniform along the length of the well and throughout the useful life of the horizontal well.

It is an objective of the invention to allow a uniform flow for horizontal well stimulation treatment through hydraulic fracturing, acidification and solvent injection methods.

It is an objective of the invention to allow treatments with scale removers to be carried out with uniform flow along the length of the horizontal well during its entire useful life.

It is an objective of the invention to allow a uniform flow in a horizontal well whose production string consists of gravel pack screens, for optional use of sand containment, throughout the life of the well.

BRIEF DESCRIPTION OF THE INVENTION

The invention addresses to a permanent flow uniformization process during the life of the oil well, which associates the use of divergent sand containment screens or divergent liner. Additionally, well stimulation, scale removal and, optionally, sand containment methods are also used.

Computational Fluid Dynamics (CFD) flow simulations are performed for the manufacture of divergent liners as a function of on the dimensions of the horizontal well, outer diameter and length of the liner, static pressure, expected flow pressure, expected oil flow rate, oil viscosity, API grade, planned length of horizontal well. These simulations simulate the area open to flow along the horizontal section.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in more detail below, with reference to the attached figures which, in a schematic way and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:

FIG. 1 illustrates the scheme of the conventional gravel pack screen;

FIG. 2 illustrates the current flow distribution scheme along the horizontal length of the well;

FIG. 3 illustrates the flow distribution scheme along the horizontal extension, with flow equalization;

FIG. 4 illustrates the scheme of the divergent screen innovation proposal;

FIG. 5 illustrates well production with and without flow uniformization technology. Curve 1 represents wells without the implemented technology and curve 2 represents wells with the implemented technology.

DETAILED DESCRIPTION OF THE INVENTION

There follows below a detailed description of a preferred embodiment of the present invention, by way of example and in no way limiting. Nevertheless, it will be clear to a technician skilled on the subject, upon reading this description, possible additional embodiments of the present invention still comprised by the essential and optional features below.

The horizontal well production method with uniform flow is described and characterized by:

-   a) designing the production string as a function of the length and     diameter of the horizontal well; -   b) sizing the perforation distribution of the horizontal well     production string according to the production string design; -   c) optimizing the perforation distribution in the production string     with a computational fluid dynamics (CFD) simulator; -   d) using holes of uniform dimensions; -   e) installing the production string of the horizontal open well     permanently; -   f) using a stimulation method; -   g) using scale removers.

The stimulation methods can be the hydraulic fracturing, acidification and solvent injection. In addition, scale removers such as DTPA (ethylenetriaminepentaacetic acid) or EDTA (ethylenediaminetetraacetic acid) can be used. Sand containment is optional. The invention can be applied in sandstone, carbonate and clastic sedimentary rock (shale) type reservoirs. The computational fluid dynamics simulator uses the horizontal well design flow rate, gas/oil ratio, reservoir pressure, flow pressure (PWF), viscosity, and API grade. The invention is also characterized by all holes having the same diameter, and the hole diameter must have values from 1 to 3 cm. The spacing and number of holes along the production string of the horizontal well are determined by computational fluid dynamics simulation.

The conventional gravel pack screens that are currently used, as shown in FIG. 1 , have the disadvantage of passing the preferential flow in the initial section of the horizontal extension of the well; this flow generates problems in the reservoir recovery factor because it allows the early formation of water cone and gas cone and because it does not guarantee a uniform reservoir production profile. Another disadvantage occurs in the longevity of the equipment, with the accelerated erosion of the screens and the possibility of early clogging of the screens.

The solution achieved by the invention to avoid the formation of early gas and/or water cones during the production of wells with long horizontal extension was the use of a process with the use of completion equipment. They are designed to perform flow uniformization along the horizontal extension of the wells to reduce gas and/or water production in the wells. This solution meets the need of reducing gas production for producing wells and increasing sweep efficiency for injection wells, through a flow uniformization process in the production of horizontal wells and/or vertical or directional wells with large extensions of net pays between producing intervals. In the case of horizontal producing and injection wells, these normally produce or inject with greater flow rate in the section closest to the beginning of the horizontal extension of the well, usually the shoe of the last casing.

In this invention, a divergent screen is proposed for horizontal producing and injection wells, equipped with mechanical containment of sand. The equalization of the production or injection flow, distributed along the entire horizontal extension of the well, is the great observed advantage. This equalization will be achieved through the conjunction of two factors in the design; firstly, the distribution of the number of holes in the base tube per screen, and secondly the positioning of these screens along the horizontal section of the well. As seen in FIG. 3 , where the dashed arrow indicates the bottomhole pressure and the solid arrows indicate the reservoir pressure.

FIG. 4 illustrates the proposal presented herein for the divergent screen, where it demonstrates the combination of the four types of screens (T1, T2, T3, and T4) . It is possible to see the sequence between the last casing shoe (5) and the bottom of the well (6).

There are advantages in case acidic treatments are needed to improve the productivity index of horizontal producing wells or to improve the injectivity index of horizontal injection wells. The divergent screens also have the advantage of allowing the treatment to be programmed using acidification tools equipped with a mechanical divergence mechanism, which is essential to achieve an efficient result. Thus, the divergent screens offer the advantage of being able to maintain the horizontal producing and injecting wells, contributing to the longevity of the designs.

The invention brings the advantage of equipment longevity, where it prevents the erosion of the screens and prevents the obstruction of the screens by produced particles. The invention also has the advantage of maximizing the reservoir recovery factor, where it decreases the possibility of water cone formation, decreases the possibility of gas cone formation, guarantees a flow in a uniform reservoir production profile and reduces the design development costs.

In horizontal injection wells, the advantage will be the better distribution of the sweep during the injection to pressurize the reservoir, which will also contribute to a maximization of the recoverable reserve, thus contributing to the longevity of the design.

The result obtained by the invention, at first, was measured using a PETROBRAS proprietary simulator; this simulator calculates the pressure drop distribution along the horizontal extension of the well. It is worth noting that other CFD type simulators can be used as well. The initial proposal of this simulator was to design a divergent screen, which provides flow equalization along the horizontal extension of the well. The idea is to design the divergent screen or divergent liner so that the number of holes designed per base tube of each screen and the sequence of positioning the screens along the sand containment system form an arrangement that provides a decreasing pressure drop from the beginning of the horizontal extension of the well to the bottom, practically inversely proportional to the flow rate per open area to the flow along the length of the production string (screens or liner). This pressure drop will be positioned directly proportional to the production flow, considering the static pressure of the reservoir as well as the flow pressure, in such a way that the contribution of each section of the set of screens of the gravel pack or divergent liner is equal along the horizontal extension. For example, at the beginning of the well, the pressure drop will be higher and at the end it will be lower. This divergent arrangement will allow flow equalization, thus optimizing production or injection along the horizontal length of the well.

Flow simulations are used to plan the manufacture of divergent liners based on information on the dimensions of the horizontal well, information such as the outer diameter of the liner and length, static pressure, expected flow pressure, expected oil flow rate, viscosity of oil, API grade, planned length of the horizontal well will be used to simulate the area open to flow along the horizontal section.

The invention of the flow uniformization process, which associates the use of divergent sand containment screens or divergent liner provides better production management and, therefore, better reservoir management.

EXAMPLE

As an example, we have the application of this technology in oil fields of the Amazon Basin, obtaining economicity in the development of the production in these fields through the application of this technology, as shown in FIG. 5 , which illustrates the application of the technology, where curve 1 (without technology of flow uniformization) shows the lower oil production in relation to curve 2, where flow uniformization technology was used with divergent perforation and throughout the life of the well with higher oil production. In this way, the invention has technical advantages due to the adequacy of the technology to the applied scenario, as well as economic advantages due to the associated cost reduction. 

1. A HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW, characterized in that there is: a) designing the production string as a function of the length and diameter of the horizontal well; b) sizing the perforation distribution of the horizontal well production string according to the production string design; c) optimizing the perforation distribution in the production string with a computational fluid dynamics (CFD) simulator; d) using holes of uniform dimensions; e) installing the production string of the horizontal open well permanently; f) using a stimulation method; g) using scale removers.
 2. THE HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW according to claim 1, characterized in that the computational fluid dynamics simulator uses the horizontal well design flow rate, the gas/oil ratio, reservoir pressure, flow pressure (PWF), viscosity and API grade.
 3. THE HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW according to claim 1, characterized in that all holes have the same diameter.
 4. THE HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW according to claim 3, characterized in that the hole diameter has a value of 1 to 3 cm.
 5. THE HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW according to claim 1, characterized in that the spacing and number of holes along the production string of the horizontal well are determined by computational fluid dynamics simulation.
 6. THE HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW according to claim 1, characterized in that it is applied in sandstone, carbonate and clastic sedimentary rock type reservoirs.
 7. THE HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW according to claim 1, characterized in that it uses the following stimulation methods: hydraulic fracturing, acidification and solvent injection.
 8. THE HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW according 1, characterized in that it uses DTPA (ethylenetriaminepentaacetic acid) or EDTA (ethylenediaminetetraacetic acid) as scale removers.
 9. THE HORIZONTAL WELL PRODUCTION METHOD WITH UNIFORM FLOW according to claim 1, characterized in that it optionally employs sand containment. 